​Most properties
managed for wildlife have at least a few food plots that get planted on an
annual basis.The for​mula for successful
wildlife plots generally involves: testing soils, liming and fertilizing as appropriate,
managing weeds, tilling, planting, and leaving the rest up to Mother Nature.However, despite following this recipe, you
may have noticed that some or all of your plots are not producing like they
used to or that they seem to be prone to failure in the summer months.The scenario might go something like this:

Your food plot looks like it is
on its way to serving as a wildlife buffet until late July and August rolls around and then things take a turn for
the worse. The once up-and-coming plot suddenly stops growing and perhaps
even fails completely and it’s off to plan B… again, for perhaps the 3rd, 4th,
or 5th season in a row. You
send off soil samples to the university for testing and the results come back
stating that that the soils are properly limed and fertilized and you are left scratching your head.

There may
be one factor that you hadn’t taken into account…hardpan.

Hardpan is
essentially a layer of soil that has become dense and compacted over years of
heavy equipment riding overhead, such as lime trucks, tractors, spray rigs,
etc. Tilling and disking a field also helps
to create hardpan as this allows fine clay particles to continually settle out
and collect just below the depth of disking. This hardpan layer can be thought of as a concrete pad from 2”-10” underneath
the topsoil that roots cannot penetrate and that water cannot drain through. Hardpan restricts root development, reduces
the ability of soils to retain moisture in the long term, and creates a field
that is prone to flooding because moisture cannot pass through the nearly
impermeable hardpan layer.

In just 3 years
time a hardpan layer can develop just several inches beneath the topsoil. When this occurs a crop will grow well up to
July until roots reach the hardpan and cannot grow any deeper. As the July and August heat comes and precipitation
decreases, the plants will appear to suffer from drought like conditions even
if Mother Nature grants us with the conditions normally necessary to maintain
healthy wildlife plantings. Additionally, even minor rains can drown out plantings because the
hardpan creates ponding and greatly increase the time a field takes to drain.

Testing for
hardpan is not difficult and can be achieved by inserting a soil probe or metal
rod directly into the soils (soil probes may be borrowed from your local
extension office, but please call ahead for availability). The probe/rod should insert fairly easily
through uncompact top soils. If hardpan
is present, it will be very noticeable as it creates a great deal of resistance
and the probe will require much more force to insert. Continue pushing through the hard pan until
you feel the resistance decrease. STOP
and mark the depth at which you felt the probe break through to less resistance
as this is the bottom of the hardpan. This
depth reading is important to know if you want to be successful at eliminating
hardpan.

Eliminating
hard pan requires the use of a subsoiling chisel plow and a tractor of at least
50 horsepower, both of which can be rented. The plow should be set to the depth that you measured the hardpan with
your soil probe. Do not set the plow
deeper as this will only serve as a waste of fuel and provide no further
benefit. This will ensure that the
hardpan is sufficiently broken, it is best to plow the entire field one-way (lengthwise)
and then go over it another time in the opposite direction (widthwise).

Hardpan is
an issue that is often overlooked and may just be the cause of crop failure if
gone unchecked for a few years. Understanding hardpan is just one more tool to
keep in your planting arsenal. The next
time you recognize a failing food plot, or if you have not subsoil plowed your
fields in the last three years, test to see if a hardpan has developed, in the
long run, it may save you money, time, and headache.

Information
like this and so much more is available at your counties Alabama Cooperative
Extension System office. Please give us
a call or make a visit!